Method and apparatus for concentrating sand



y 1962 c. c. HOBART, SR 3,033,371

METHOD AND APPARATUS FOR CONCENTRATING SAND Filed May 20. 1959 CHARLES C. HOBART 5);

LJ 20 38 4- f/ jww ited Stftes fice 3,033,371 METHOD AND APPARATUS FOR CONCEN- TRATING SAND Charles C. Hobart, Sr., Hobart Cabinet Company, Troy, Ohio Filed May 20, 1959, Ser. No. 814,541 5 Claims. (Cl. 209-458) This invention relates to an arrangement for and a method of separating particulate materials such as sand so as to concentrate heavy components thereof so that valuable portions of heavy components can be collected in a sufiicient degreeof concentration to enable economical refining thereof.

It is known that many sand deposits contain components which are commercially valuable and which war-' rant the time and expense of recoverysthereof from the sand provided the recovery can be accomplished at. suf: ficiently low cost. Such heavy component's comprise titanium, and zirconium compositions, monazite and other minerals.

It has been found that the components referred to above, and which are about twice as heavy as the ordinary silica sand, can be recovered by admixing the sand with water to form a slurry and then causing the slurry to flow along an incline or the like, a sulficient distance for the slurry to stratify with the heavier portion along the bottom of the flowing stream of slurry. The flowing stream is then split by splitter blades or skimming blades and in this manner the heavier fraction of the slurry is split off and a product sufiiciently high in the valuable heavy minerals is obtained to warrant the' further processing thereof.

Heretofore, the processing of sands to separate the heavy component therefrom has been carried out in specially designed sand splitting or separating devices which usually embody a multiplicity of inclined sluice arrangements either straight or spiral and into which a slurry of sand or water is fed by pumps and with the material being split in the described manner as it emerges from the sluice or it passes along the slurry. Usually the material being processed is passed through a plurality of skimming or splitting stations and this sometimes involves delivering the material to storage tanks intermediate the stations and the subsequent pumping from the storage tanks.

The use of specially designed apparatus of the nature referred to for separating sand into it heavy and light fractions has certain outstanding disadvantages. If the apparatus is of a fixed nature, it becomes necessary to convey large quantities of sand to the apparatus in order to obtain the small fraction therefrom that is to be further processed to obtain the valuable heavy minerals.

Sand separating devices are sometimes mounted on barges or the like whereby the apparatus becomes mobile. An arrangement of this sort generally involves the problem of dislodging sand in large quantities from beneath the surface of water on which the barge floats or immediately adjacent the edge thereof with the dislodged sand being pumped upwardly to the separating apparatus carried by the barge.

This arrangement also therefore has a marked disadvantage in connection with the handling and moving of the material that is to be processed.

Another disadvantage in connection with sand separators of the nature referred to is that they are quite expensive and large and thus represent considerable investment and require a great deal of maintenance to maintain them in good operating conditions.

Thus, the methods now in use for separating and accumulating these heavier minerals in sizable quantities from the sands, usually require a dredge, a screen, slurry control equipment, tapering troughs or spirals, adjustable separating mechanisms, often called splitters, tanks for different stages of concentration and pumps for moving away the unwanted material etc.

The procurement, upkeep, and proper management of this is expensive and complex. All of this is not particularly efiicient as further concentration methods must be finally used.

Having the foregoing in mind, it is a primary object of this invention to provide an arrangement for treating sands so as to concentrate the heavy mineral portion thereof to a commercially valuable concentrate without the use of expensive bulky apparatus.

A still further object is the provision of a novel arrangement for separating sands so as to arrive at a commercially valuable heavy concentrate thereof which permits separation of the sand with the least handling of the sand.

A' still further object of this invention is the provision of a method of treating sand to obtain in concentrated form a heavy mineral fraction therefrom in which a minimum of expense is required and in connection with which ordinary earth moving devices can be employed for handling the sand and ordinary water handling equipment to effect the sand concentration.

It is still a further object of this invention to provide an arrangement for and a method of separating sands to yield a heavy mineral concentrate in which the disposing of lighter fractions of sand, and which is by far the greater fraction by volume, is accomplished without difficulty.

One object of this invention is to avoid screening. All roots, sticks, and trash are soon washed away.

Another object is to avoid the need for manual correction for various percentages of heavy mineral contained in the sands to be washed.

Another very important object is to provide for progressive concentration high enough and accumulation in quantilties large enough to be moved to the final processing p ant.

Another object is to dispose of the lighter sands or tailings economically.

These and other objects and advantages will become more apparent upon reference to the drawings in which FIGURE 1 is a sectional view showing one manner in which this invention can be practiced;

FIGURE 2 is a sectional view drawn at enlarged scale showing the action of the water on the sand, and is indi cated by line 2-2 on FIGURE 1;

FIGURE 3 is a plan view of the arrangement;

FIGURE 4 is a view like FIGURE 3 showing a concentration of heavy mineral in about the center of the sand ridge, and

FIGURE 5 is a view looking in at the sand ridge from the nozzle position.

In general the present invention deals with the separation of sand so as to separate therefrom the small heavy mineral fraction by so arranging the sand in a ridge that it can be washed by a stream of water from a nozzle which will create such hydraulic conditions that the lighter portion of sand will flow off with the water in the form of a slurry of tailings while the heavy valuable mineral portion of the sand will settle out without running ed with the tailings in a location where the heavy portion can be picked up.

Treatment of the sand in bulk in the manner referred to above involves placing the sand so that a large amount thereof can be subjected to a water stream or jet and then establishing a proper drainage path for the tailings and a proper collection region for the heavy concentrate.

This is done by pushing the sand into a ridge with earth moving machinery or by establishing an arcuate surface in the side of a mound or hill made up of sand. The

3 region in front of the bottom of the arcuate ridge forms the area within which the heavy components are to collect and leading down away from this area toward the center of the curvature of the arcuate ridge is a drain area for tailings which is inclined at such an angle that the tailings will remain in suspension in the water while the heavy component will settle out in the aforementioned area at the base of the ridge.

A nozzle is provided at about the center of curvature of the ridge and is supplied with water under pressure so as to direct a stream of water against the ridge and is actuated for sweeping back and forth laterally along the ridge thus dislodging the sand therefrom in the form of a slurry and which slurry tends to separate in the region at the base of the ridge so that the larger part of the heavy component remains thereon while the larger part of the tailings or light fraction passes on down to the drainage passage to discard.

When a sufficient quantity of the heavy component is thus deposited 'it can be removed to a refining plant, or it can be further concentrated in a mineral separator, or it can be moved to another place in the arcuate ridge to be further washed if so desired.

Referring now to the drawings more in detail, FIG- URES 1 and 3 show the manner in which the arcuate ridge can be formed which might be at the base of a hill or a mound of sand but which, preferably, is provided by pushing sand into the form of a curved ridge by earth moving machinery.

The ridge as mentioned is arcuate and is preferably formed as an arc of a circle about an axis 14 on which is located a sled mounted monitor or nozzle 16 that directs a somewhat looping jet or stream of water 18 across to the ridge 10 and along the region 20 disposed up- Wardly from the base of the ridge. The ridge is defined by marking a segment of a circle with a tape attached to the sled on which the monitor or nozzle is mounted. Nozzle 16 may be carried on the sled 22 so that it is readily portable; whereby after one region is exhausted the sled can be moved to a new location thus reducing the distance that the sand to be treated would have to be moved.

Nozzle 16 is adapted for being supplied with water under pressure by a pump 24 and which pump draws water via a conduit 26 from an adjacent body of water 28 which may be a lake, pond, stream or the ocean.

Leading from the base of ridge 10 along about a 20% incline is a region 36 over which the tailings pass to a drainage ditch or channel 33 through which the tailings pass to the body of water which is adjacent the treatment position. The channel may overflow water via channel 40.

The heavy jet of water from the nozzle is then turned laterally, sweeping the length of the ridge repeatedly at a height of about 2 feet above the base of the ridge. This will maintain a slope of about 20 degrees and the sand will feed itself down. With a uniform application of water to the ridge at equal distances from the monitor and a 20 degree slope away from the base of the ridge, there will be a mild fiow of water and sand along the full length of the ridge which will deposit a layer of heavier mineral with each sweep of the water and lighter sand will be carried beyond. The heavy mineral will deposit out to about 12-15 feet from the base of the ridge.

When the ridge has had repeated lateral washings, the deposit of heavy mineral out from the base of the ridge may be tested with a hand shovel, turning up samples.

This area of heavier concentrates is darker in color than the lighter sands as indicated at 42. After repeated washings the ridge is again marked and the darker sand in area 42 is pushed up by tractor or loader, making a smaller but more concentrated ridge than before.

When the concentration appears dark enough, the best of it is moved to a single position in the ridge for higher concentration as at 44 in FIGURE 4. This provides for adjoining sand in the ridge on each side of the highly concentrated material, so that it may accumulate and progressively concentrate at 46 under uniform washing conditions with each sweep of the stream of water.

The lighter sand is carried as the water flows, narrowing towards the center, increasing in speed and volume per square foot, and goes into the disposal ditch, 38.

The water from here flows back into the pond and the accumulated tailings are pused on and out beyond by tractor or other methods, as indicated by arrow 48.

I find it important in the practice of the present invention for the sand to be arranged in an arcuate ridge substantially concentric with the laterally turning nozzle but it will be understood that exact concentricity is not absolutely essential.

From the foregoing it will be appreciated that the present invention discloses a method of treating sands in bulk, by utilizing substantially conventional earth moving and water handling equipment whereby extremely large quantities of sand can be treated rapidly and resulting in the yield of a large volume of heavy concentrate.

It is to be pointed out that the present invention differs from known placer mining methods in that wherein placer mining the purpose is to dislodge large quantities of earth for movement to a processing station by the use of an extremely high pressure water jet. In the present case a lower pressure jet of large volume is employed thereby giving a looping stream of Water and with the region of treatment being formed so as to be substantially concentric to the laterally turning nozzle and with a separating action being had immediately adjacent the treatment region. There is thus a basic difference between the method of the present invention and known placer mining methods.

With the present invention What occurs is that the light sands are washed away leaving the heavier sands behind. The heavier sands thus take only a small movement as opposed to conventional separating practices wherein the heavier sands are moved along with the light sands and are separated therefrom by stratification of the heavier sands into the bottom of the moving stream of mixed sands and by being taken out from the stream of mixed sands while in motion. In the method of the present invention, while the mixture is moving, the lighter sands separate from the heavier sands and are washed away leaving a heavier mixture. Generally, it is only after many rinsings that the heavier sands become sufiiciently highly concentrated to justify transferring thereof to a refining plant.

It will be understood that this invention is susceptible to modification in order to adapt it to different usages and conditions and, accordingly, it is desired to comprehend such modifications within this invention as may fall within the scope of the appended claims.

I claim:

1. A method of concentrating valuable heavy minerals from sands which comprises the steps of establishing an arcuate ridge of said sands, directing a looping stream of water from a source arranged at approximately the center of the curvature of the arcuate ridge and against the ridge along a concentric area spaced upwardly from the base of the ridge and from end to end of the ridge whereby a slurry of sand and water is produced which flows unidirectionally down said ridge from said concentric area toward the base of the ridge and then away from the ridge, maintaining a predetermined incline away from the base of said ridge so that the heavy component of the sand in said slurry settles out adjacent the base of said ridge, draining said water and the light sand down said incline and away from the base of the ridge, and moving said heavy component from along the base of the ridge to a central position in said ridge and re-forming the ridge and continuing the washing of the entire ridge to progressively increase the percentage of the heavy component in said central position of the ridge by washing the lighter sand therefrom.

2. A method of concentrating valuable heavy minerals from sands by hydraulically treating said sands, comprising the steps of forming said sands into an arcuate ridge with an incline leading from the base of the ridge toward the center of curvature thereof, repeatedly washing the ridge from end to end along a concentric arcuate line spaced upwardly from the base with a looping stream of water whereby a slurry of sand and water flows down the ridge onto the incline, the degree of the in cline being such that a heavy component of the sand remains on the incline adjacent the base of the ridge while the lighter component flows on down the incline and away from the base of the ridge periodically moving the heavy component radially back into the ridge and carrying out further washing operations on the ridge thereby further to concentrate said heavy component along the base of the ridge, and still further concentrating the deposits of heavy mineral component by moving the same from along the entire length of the base of the ridge up into a relatively short region in the central section of said arcuate ridge and continuing the washing of the ridge whereby the heavy component of the sand accumulates in the region of said center section of the ridge and is brought up to a high degree of concentration.

3. In an arrangement for concentrating the valuable heavy components from sands, an arcuate ridge of sand, means disposed at about the center of curvature of the ridge for directing a looping stream of water along a line against the ridge spaced upwardly from the base thereof, means for moving said stream from end to end of the ridge, an inclined region extending from the base of the ridge toward the center of curvature thereof, and means of further concentrating the heavy mineral component which accumulates along the base of the ridge with earth moving equipment for moving the accumulated heavy component into a small space in the arcuate ridge for continued washing, the degree of said inclined region being such that heavy components will settle out thereon adjacent the base of the ridge While the light components will pass thereover with the water.

4. In an arrangement for concentrating valuable heavy minerals from sands, an arcuate ridge of sand, movable means positioned at about the center about which the curvature of the ridge is formed and comprising a pressurized nozzle for directing a looping stream of water against the ridge upwardly from the base thereof, said nozzle being adapted for oscillating to traverse the ridge from end to end, means forming an inclined region along the base of the ridge extending downwardly away from the ridge on the nozzle side thereon, said inclined region of such inclination that a sand-water slurry flowing down the ridge and on to said region will drop the heavy component on the inclined region adjacent the base of the ridge while the light component is washed away by the water, and means for moving the heavy mineral accumulated at the base of the ridge radially back into the ridge for further washing and for then moving the heavy mineral at the base of the ridge circumferentially and radially into a central position in the ridge for still further washing whereby a large bulk of heavy concentrate accumulates at the base of the ridge at the said central position thereof so that it becomes economically practical to remove it to the refining plant.

5. A process for separating, accumulating and concentrating heavy sand from a mixture of light weight and heavy weight sands, with commercial earth and water moving equipment, which consists of forming the mixed sands into an arcuate ridge with a slope leading away from the base of the ridge, and repeatedly washing out light sand from this ridge and the slope by directing a stream of water from the center of curvature of the ridge against the ridge and along a line spaced upwardly on the ridge from the base thereof, traversing the stream horizontally back and forth along the ridge so that a slurry of water and light sand flows unidirectionally down the ridge and over the slope thereby effecting a separation of the sand by removing the lighter weight sand beyond the heavier sand on the slope at the base of the ridge, while simultaneously leaving the partially separated heavier component of the sand on the slope adjacent the base of the ridge, periodically replacing this partially separated heavier component back into the ridge in distributed relation therein, again repeatedly washing the ridge in the aforesaid manner; continuing steps of washing the ridge and periodically replacing the partially separated heavier component of the sand back into the ridge until a predetermined degree of concentration of the heavier component of the sand that is accumulated on the slope is achieved, re-forming the ridge and moving the accumulated partially separated heavier component of the sand from the slope into a predetermined limited short region of the re-formed arcuate ridge and effecting the concentrating of this accumulation of the heavier component of the sand at the base of the said limited short region of the ridge by further washing of the ridge in the aforesaid manner to wash light weight component of the sand therefrom.

References Cited in the tile of this patent UNITED STATES PATENTS 295,992 Farifield Apr. 1, 1884 1,424,339 Burgess Aug. 1, 1922 1,810,571 Mead June 16, 1931 FOREIGN PATENTS 4,715 Great Britain Nov. 20, 1879 355,269 Great Britain Aug. 20, 1931 OTHER REFERENCES Mining Engineering, eleven pages, 421-429, April 1959. 

